Fixed Drive / Friction Drive
The fixed drive is characterised by a form-fit and force-fit connection between the drive head and the load-bearing tube. There is no friction, the drive torque is fully transmitted. Slippage within the power transmission is not anticipated.
The friction drive is based on the principle of the slip coupling. It offers the option of setting up an accumulation conveyor very cost-effectively with minimal accumulation pressure.
The construction thus requires very few drives, with segmentation being provided by mechanical stoppers. The bearing housing of the Series 3800 is designed as a greased-for-life slip coupling and thus guarantees the roller's constant conveyor force. The tangential chain drive has proved itself to be especially economical when used on friction conveyors. A central drive drives a long chain underneath the conveyor so that all of the rollers are operated.
If an accumulation should occur, then the rollers under the material to be transported stand still and only the drive heads continue to rotate. It should be noted that the accumulation pressure is cumulative with the length of the accumulated material to be transported. In this way the containers are able to absorb the accumulation pressure without becoming deformed. The design should also prevent the containers from being pried out owing to the increasing accumulation pressure. The friction drive is available for straight conveyor segments and also for curves.
Conveyor force of the friction drive
The conveyor force produced by friction by the friction roller regulates itself relative to the weight of the material to be transported. The conveyor force is seriously affected by the following factors:
• Weight of the material to be transported
• Condition of the base of the material to be transported
• Percentage of accumulation mode over the entire running time
These factors have, to an extent, a considerable effect on the operation and operational lifespan of the conveyor roller. Accumulation mode should only be used for as long as is necessary. When it can be seen that no conveyance will take place, then the central drive should be switched off. No energy will be used and the lifespan of the conveyor system will be increased. We would recommend discussing your individual application with Interroll experts and also conducting an operational test with the original materials to be transported.
The following conveyor values are non-binding and relate to a normal environment (65 % relative air humidity and a temperature of +20 °C) and to the material to be transported sitting centrally on the conveyor rollers. The figures will be markedly different if the load centre is not central. The figures will fall the further the load centre is from the drive element. Even and stable bases of the materials to be transported are ideal so that each roller carries the material evenly.
The following conveyor power is produced depending on the roller load:
• 4 to 6 % with one-sided friction coupling and Ø conveyor roller 50 mm
• 2 to 5 % with one-sided friction coupling and Ø conveyor roller 60 mm
• 8 to 13 % with two-sided friction coupling and Ø conveyor roller 50 or 60 mm
• 4 to 6 % with load-dependent conveyance, adjustable up to approx. 12 % of the roller load by additional axially adjustable friction coupling
The permissible conveyor speed is 0.5 m/s. Flanges and other side guides are not recommended with friction rollers as the static friction produced may not be overcome by the conveyor force of the friction coupling. Accumulation in curves with friction rollers should always be avoided. If accumulation is to occur in curves, then only zero pressure accumulation systems, such as RollerDrives can be employed.